This invention relates to a control for a refrigerator incorporating two evaporators, one of which is maintained at a below freezing temperature for cooling the freezer compartment and the other of which is maintained at a higher above freezing temperature for cooling the fresh food compartment and more particularly, to an electronically controlled valving system that delivers refrigerant to the fresh food evaporator in preference to the freezer evaporator and directs flow of refrigerant to the freezer evaporator after a predetermined amount of time independent of the fresh food compartment temperatures.
Refrigeration systems incorporating a single condenser that delivers refrigerant selectively to one or the other of two evaporators are well known. In U.S. Pat. No. 1,523,112, the thermostat in either compartment causes refrigerant flow to its respective evaporator, however, in the case when both thermostats call for cooling refrigerant will be diverted to the colder below freezing compartment. In U.S. Pat. No. 2,133,957, when the demand for cooling is from both of the compartments, the low temperature evaporator is given preference. At such times, the higher temperature compartment is not being refrigerated and may rise in temperature to an abnormally high value. In this event, means are provided for transferring refrigeration to the high temperature evaporator. It should be noted that this rise in temperature may be over a long or extended period of time in which event food in the higher temperature compartment may be subjected to these relatively high temperatures for a substantial period of time that may be sufficient to cause food spoilage. In U.S. Pat. No. 2,576,663, the fresh food compartment evaporator has preference when both compartments require cooling and the freezer evaporator is activated only after the fresh food evaporator and fresh food compartment temperature is satisfied. A fan that runs during operation of either evaporator effectively removes any accumulated frost from the fresh food evaporator when the freezer evaporator is activated by circulating the above freezing fresh food compartment air over the fresh food evaporator.